It has four "12G-SDI" (12G meaning it supports a 12Gb/s bitrate) inputs, plus an HDMI one. The SDI ones are IN/OUT so you can chain different equipment.

SDI is a common interface type for professional video equipment - unlike HDMI/DP/etc. it's not encrypted (no DRM), thereby usually not available on consumer equipment because it would allow to easily copy the data stream...